Grinding



R. J. LEVI GRINDING Sept. 20, 1966 2 Sheets-Sheet 1 Filed Feb. 26, 1963 p 20, 1966 R. J. LEVI 3,213,290

GRINDING Filed Feb. 26, 1963 2 Sheets-Sheet 2 INVENTOR A owns United States Patent Qfiice 3,273,250 Patented Sept. 20, 1966 3,273,290 GRINDING Richard J. Levi, 256 Irving Ave., Cluster, NJ. Filed Feb. 26, 1963, Ser. No. 261,026 Claims. (Cl. 51-165) This invention relates to a machine for grinding one or more dimensions of metal machine parts to precise dimensions by remote electronic control.

An object of the present invention is to provide a basis for improved economy and efiiciency in a simplified 2 axis table readily adaptable to partial or total automatic programming by switchboard dialing, punched tape or any other numerically controlled means. This is by virtue of the electro-mechanical servo and accessory components depicted in FIGURES l and 2 and in the accompanying description and claims.

Other objects and advantages of the invention will become more apparent through reference to the ensuing description and appended claims, and drawings wherein:

FIG. 1 is a detailed assembly drawing of the table feed and retraction servo-mechanism of the present invention showing the method of engaging, fine feeding, stopping and retracting the machine table, and illustrating the subassembly mechanism operative on the basis of an energy storage principle for backlash control and retraction with direction memory; and

FIG. 2 is a partial view, partly in section, showing in detail the magnetic braking sub-assembly used in the mechanism of FIG. 1.

The mechanism of the present invention is comprised of the following elements and sub-assemblies:

(l) A conventional plain grinder equal to any One of the various types commonly used in machine shops for finishing metal parts between centers to finite dimensions.

(2) A servo-mechanism and feed vernier combined (see FIGS. 1 and 2) incorporated for the purpose of feeding the machine table which contains the metal part to be ground on centers against the side of the grinding wheel at a rate which is controllable to a resolution of 20 millionths of an inch per step division of the hand or motor driven Vernier. This subassembly includes a worm directly associated with the Vernier, a rack to which the worm can be engaged and disengaged electrically and a gear train which obtains its motion from the rack. The rack is coupled to a compression spring in such a way as to cause a self-storing of energy by turning the Vernier, which energy is released on signal in a direction opposite to that which is imparted by the vernier. This element constitutes energy storage, directional memory and backlash elimination combined in one. The signal is one of three electric actions in the sub-assembly as follows:

(a) A magnetic clamp on the Vernier worm shaft which, when switched to power by a pre-arranged signal, has the effect of stopping the feed permitting no override or drift.

(b) An engagement solenoid which acts as a clutch to maintain the gear train in fine feed.

(c) The retraction solenoid and linkage which, when deenergized, releases the above described spring stored energy in the direction opposite to feed.

(3) A suitable feed servo package for feeding the wheel carriage, stopping and retracting it by electric means such as is conventionally combined with, or can be added to, plain or universal cylindrical grinders, e.g., hydraulic cylinder, electric motor.

A description of the operation of the mechanism illustrated in FIGS. 1 and 2 follows:

FIG. 1 discloses a mechanism and feed Vernier combined for the purpose of feeding a machine table, which contains the metal part to be ground on centers against the side of a grinding wheel. As shown in FIG. 1, an input shaft 11, which can be manually rotated by the knob 13, drives a worm 15. The worm 15 drives a gear 17, which is directly coupled to a gear 15, which drives a rack 21. The foregoing system is appropriately connected to the elements of the grinding machine in. a conventional manner so that by turning the knob 13, the rack 21 can be advanced and the part to be ground (supported by the machine table) is simultaneously moved against the grinding wheel.

Motion of the rack 21 is opposed by compression spring 23 which biases the rack 21 to a starting position and serves to remove backlash from the gear train assembly driving the rack 21 from the input shaft 11, comprising the worm 15, the gear 17 and the gear 19. An electric brake 25 (see FIG. 2 for details) is provided on the shaft 11 and, when energized, the brake 25 will prevent further rotation of the shaft 11. In response to an input signal indicating that the part being ground is approaching the desired dimension, the brake 25 is energized to stop rotation of the shaft 11 and thus stop further advance of the rack 21 and the machine table.

The input shaft 11 is pivotable about a pivot point 27. When the shaft 11 pivots about the pivot point 27 the worm 15 will disengage from the gear 17. By means of a linkage mechanism 29, the shaft 11 is latched in the position shown in FIG. 1 and held in engagement with the gear 17. A spring 31 is provided tending to pivot the shaft 11 to move the worm 15 out of engagement with the gear 17. A solenoid is provided to be selectively operable to release the latch on the linkage 29 so that the spring 31 will cause the shaft 11 to pivot about pivot point 27 and move the shaft 11 out of engagement. When the worm is pivoted out of engagement with the gear 17, the spring 23 will drive the rack 21 back to its starting position and thus move the workpiece away from the grinding wheel.

In operation, after the brake 25 has been energized to stop the advance of the table, the grinding wheel will then continue to grind the workpiece although the table will not be advancing. When the workpiece has been ground to the precise dimension, a signal will energize the solenoid, releasing the latch mechanism and allowing the spring 31 to pivot the worm 15 out of engagement with the gear 17. Accordingly, the spring 23 will then drive the rack 21 back to its starting position and the machine table will carry the workpiece away from the grinding wheel. In this manner, the workpiece is ground to the precise desired dimension.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

I claim:

1. A mechanism for controlling relative motion between a machine tool and a workpiece comprising: a movable member for providing relative motion between a machine tool and a workpiece, a rotatable input shaft, drive means operable when engaged to drive said movable member from the rotation of said input shaft, biasing means to expose the motion of said movable member and bias said movable member back toward a starting position to thereby eliminate backlash from said driving means, means selectively operable to brake said input shaft, and means selectively operable to disengage said driving means so that said biasing means will drive said movable member 3 back to said starting position moving the workpiece and the machine tool away from one another.

2. A mechanism for controlling the relative motion between a machine tool and a workpiece comprising: a movable member for providing relative motion between a machine tool and a workpiece, a rotatable input shaft, driving means operable when engaged to drive said movable member from the rotation of said input shaft, a spring positioned to oppose the motion of said movable member and bias said movable member back toward a starting position to thereby eliminate backlash from said driving means, means selectively operable to brake said input shaft, and means selectively operable to disengage said driving means so that said spring will drive said movable member back to said starting position moving the workpiece and the machine tool away from one another.

3. A mechanism for controlling the relative motion between a machine tool and a workpiece comprising: a movable member for providing relative motion between a machine tool and a workpiece, an input shaft pivotable between a first position and a second position, a worm fixed on said input shaft, a gear system positioned to be engaged by said worm when said input shaft is in said first position and disengaged by said worm when said input shaft is in said second position and operable to drive said movable member from the rotation of said input shaft when said input shaft is in said first position, biasing means to oppose the motion of said movable member and bias said movable member back toward a starting position to thereby eliminate backlash from the drive comprising said worm and said gear system, means selectively operable to brake said input shaft, and means selectively operable to pivot said input shaft from said first position to said second position so that said worm disengages from said gear system and said biasing means drives said movable member back to said starting position moving the workpiece and the machine tool away from one another.

4. A mechanism for controlling the relative movement between a machine tool and a workpiece comprising: a drive system including (a) a rotatable input shaft pivotable between a first position and a second position, (b) a worm fixed on said input shaft, (c) a first gear positioned to be engaged by said worm when said input shaft is in said firs-t position and disengaged from said worm when said input shaft is in said second position, (d) a second gear driven from said first gear and (e) a rack engaged by said second gear so that when said input shaft is in said first position said rack will be driven by said input shaft; said drive system being connectable to provide relative movement between said machine tool and said workpiece upon rotation of said input shaft; a spring positioned to oppose the motion of said rack and bias said rack back toward a starting position to thereby eliminate backlash from said drive system; means selectively operable to brake said input shaft; and means selectively operable to pivot said input shaft from said first position to said second position so that said worm is disengaged from said first gear and said spring is allowed to drive said rack back to said starting position so as to move the workpiece and the machine tool away from one another.

5. A mechanism for controlling the relative motion between a machine tool and a workpiece, comprising: a movable member for providing relative motion between a machine tool and the workpiece; driving means operable when engaged to drive said movable member from an input; biasing means to oppose the motion of said movable member and bias said movable member back towards a starting position to thereby eliminate backlash from said driving means; means selectively operable to brake said driving means; and means selectively operable to disengage said driving means so that said biasing means will drive said movable member back to said starting position moving the workpiece and the machine tool away from one another.

References Cited by the Examiner FOREIGN PATENTS 5/1931 Great Britain.

OTHER REFERENCES American Machinist-Metalworking August 7, 1961, vol. 105, No. 16, page 75.

LESTER M. SWINGLE, Primary Examiner. 

1. A MECHANISM FOR CONTROLLING RELATIVE MOTION BETWEEN A MACHINE TOOL AND A WORKPIECE COMPRISING: A MOVABLE MEMBER FOR PROVIDING RELATIVE MOTION BETWEEN A MACHINE TOOL AND A WORKPIECE, A ROTATABLE INPUT SHAFT, DRIVE MEANS OPERABLE WHEN ENGAGED TO DRIVE SAID MOVABLE MEMBER FROM THE ROTATION OF SAID INPUT SHAFT, BIASING MEANS TO EXPOSE THE MOTION OF SAID MOVABLE MEMBER AND BIAS SAID MOVABLE MEMBER BACK TOWARD A STARTING POSITION TO THEREBY ELIMINATE BACKLASH FROM SAID DRIVING MEANS, MEANS SELECTIVELY OPERABLE TO BRAKE SAID INPUT SHAFT, AND MEANS SELECTIVELY OPERABLE TO DISENGAGE SAID DRIVING MEANS SO THAT SAID BIASING MEANS WILL DRIVE SAID MOVABLE MEMBER BACK TO SAID STARTING POSITION MOVING THE WORKPIECE AND THE MACHINE TOOL AWAY FROM ONE ANOTHER. 